Create a module to install Flux to the cluster

Background

We did a spike on using Flux as a Gitops tools and the things the CP team and users need to do to use this Gitops way of deploying the applications.

As a result CP team want to try using Flux to deploy CP team apps i.e. HOODAW, CANARY-APP etc. To do that, we need the controller installed in the cluster.

This ticket is to create a terraform module to deploy flux-system into the cluster as part of infrastructure.

More information on the ticket: https://github.com/ministryofjustice/cloud-platform/issues/3476 and the doc here: https://docs.google.com/document/d/1wTJ0RCItIAcXus3tbrGG47-MfSt5WOgUfhkLsmlC10k/edit?usp=sharing

Which part of the user docs does this impact

https://github.com/ministryofjustice/cloud-platform-infrastructure https://github.com/ministryofjustice/cloud-platform

Questions / Assumptions

How does the upgrade of flux looks like? Does this break any existing flux controller CRDs and objects created ?

Definition of done

[ ] Module created for flux and installed to the live cluster
[ ] readme has been updated
[ ] user docs have been updated
[ ] another team member has reviewed
[ ] smoke tests are green

Reference

How to write good user stories

ministryofjustice / cloud-platform